The study presented in this paper evaluates cumulative energy consumption solely for traction including recuperation (if any), well-to-wheel greenhouse-gas emissions, and operating costs for diesel, CNG and supercapacitor electric buses in case of their operation on Belgrade’s radial public transport line 27. A physics-based longitudinal-dynamics model was calibrated with actual speed profile, altitude, and passenger-load data collected in field tests, then applied to two complete cycles (Republic Square ↔ Mirijevo 3). Results show that the e-bus energy balance (consumption - recuperation) was only 47.9 MJ per half-cycle, yielding energy savings of 71% relative to the diesel bus and 82% relative to the CNG bus. Corresponding unit energy balance per fuel were 4.74 MJ/km for electric, 16.23 MJ/km for diesel and 25.64 MJ/km for CNG powered buses. Despite Serbia’s coal-dominated electricity mix, well-to-wheel CO2 emissions from the e-bus remained the lowest at 0.73-0.74 kg/km, while tail-pipe emissions of CO, NOₓ, and PM were eliminated entirely. Comparative analysis confirmed that road gradient and stop density dominate energy demand in case of equivalent driving style (i.e., excluding driver’s impact). The findings demonstrate that electric buses can deliver substantial energy and local-pollution benefits even on hilly, mixed-traffic routes, providing actionable evidence for fleet managers and policy-makers